1. Field of the Invention
The present invention relates to a vibration-proof mount (or mounting, or mounting element) for use in supporting a driving source of a vehicle on a vehicle body.
2. Description of the Related Art
Conventionally, this kind of vibration-proof mount is made up of an inner cylinder, an outer cylinder and a vibration-proof member such as rubber, or the like, which connects the inner cylinder and the outer cylinder. One of the inner cylinder and the outer cylinder is connected to the vehicle body and the other thereof is connected to the driving source.
In this kind of vibration-proof mount, there is also known one in which axial perforations are formed in the vibration-proof member. In this conventional vibration-proof mount, the spring constant of the vibration-proof mount becomes small until the perforation is crushed, with the result that the fine or small vibrations can be efficiently absorbed. Once the perforations have been crushed, the spring constant of the vibration-proof mount becomes large, with the result that large vibrations can also be effectively absorbed.
However, in the case of the vibration-proof mount for an electric motor which serves as the driving source of an electric vehicle, the perforations cannot be formed in the vibration-proof member in view of the frequencies of the vibrations which are generated in the electric motor.
In view of the above point, the present invention has an object of providing a vibration-proof mount in which a function of switching the spring constant can be obtained even in such a solid type of vibration-proof mount that perforations are not formed in a vibration-proof member.